The key difference between prokaryotic and eukaryotic DNA is that the prokaryotic DNA freely floats in the cytoplasm while the eukaryotic DNA situates inside the nucleus.
There are two major categories of living organisms such as prokaryotes and eukaryotes. They differ from each other by their cellular organization. Accordingly, prokaryotes have a simple cellular organization. They lack a nucleus and membrane-bound organelles. On the other hand, eukaryotes have a complex cellular organization. They have a true nucleus that contains DNA and also membrane-bound cell organelles. All the prokaryotes are unicellular while eukaryotes may be unicellular or multicellular organisms. Prokaryotes and eukaryotes mainly contain DNA genomes. Their DNA is packaged into chromosomes. Since prokaryotes do not have a nucleus, their DNA freely floats in the cytoplasm. However, in eukaryotes, chromosomes situate inside the nucleus. Hence, nuclear membrane encloses all eukaryotic DNA.
CONTENTS
1. Overview and Key Difference
2. What is Prokaryotic DNA
3. What is Eukaryotic DNA
4. Similarities Between Prokaryotic and Eukaryotic DNA
5. Side by Side Comparison – Prokaryotic vs Eukaryotic DNA in Tabular Form
6. Summary
What is Prokaryotic DNA?
There are two main groups of prokaryotes such as bacteria and archaea. They are unicellular tiny organisms. Both these categories have a single chromosome as their genome. Thus, it is mostly a DNA genome. This single chromosome is a circular chromosome made up of double-stranded DNA.
Moreover, it freely floats in the prokaryotic cell cytoplasm. Prokaryotic chromosome is compact, and it does not contain repetitive DNA and introns. Though prokaryotic DNA is packaged into a single chromosome, this DNA does not fold with histone proteins. Prokaryotic DNA coils with nucleoid-associated proteins.
Figure 01: Prokaryotic DNA
In addition to this chromosome, prokaryotes have extra-chromosomal DNA called plasmids. Plasmids are small DNA circles. They do not contain genomic DNA of prokaryotes. Instead, they contain genes that provide beneficial effects to the bacterial cell. Plasmids are important as valuable vectors in genetic engineering.
What is Eukaryotic DNA?
Eukaryotes have a true nucleus that encloses with a nuclear membrane. Hence, eukaryotic DNA resides inside the nucleus by enclosing the nuclear membrane. However, some non-genomic eukaryotic DNAs are found outside the nucleus, within two types of cell organelles. They are chloroplasts and mitochondria. Unlike prokaryotic DNA, eukaryotic DNA contains many repetitive DNA which is non-coding.
Figure 02: Eukaryotic DNA
Furthermore, eukaryotic DNA contains introns other than exons. Therefore, the amount of eukaryotic DNA per cell is very high compared to the amount of prokaryotic DNA. Not only that, eukaryotic DNA folds with histone proteins and packages into several chromosomes. Hence, eukaryotes contain more than one chromosome, unlike prokaryotes. The human genome contains a total of 46 chromosomes. Generally, eukaryotes do not have plasmid DNA. But several types of eukaryotes have plasmid DNA.
What are the Similarities Between Prokaryotic and Eukaryotic DNA?
- Prokaryotic and eukaryotic DNAs are double-stranded helical structures.
- Both are composed of deoxyribonucleotides.
- Also, both contain four types of nitrogenous bases (A, T, C and G).
- Furthermore, both types of DNA contain genetic codes/information for the synthesis of proteins.
- Besides, both types of DNA can self replicate.
What is the Difference Between Prokaryotic and Eukaryotic DNA?
Prokaryotic DNA is present in the cytoplasm while the eukaryotic DNA is present inside the nucleus. Thus, this is the key difference between prokaryotic and eukaryotic DNA. Furthermore, prokaryotes have only one chromosome while eukaryotes have more than one chromosome.
Moreover, another difference between prokaryotic and eukaryotic DNA is that the prokaryotic DNA contains less number of genes than the eukaryotic DNA. Also, a further difference between prokaryotic and eukaryotic DNA is that the prokaryotic DNA does not contain repetitive DNA and introns while eukaryotic DNA contains a lot of repetitive DNA and introns. Additionally, the amount of prokaryotic DNA is small compared to the amount of eukaryotic DNA. Therefore, it is also a difference between prokaryotic and eukaryotic DNA.
The below infographic presents more details of the difference between prokaryotic and eukaryotic DNA.
Summary – Prokaryotic vs Eukaryotic DNA
Prokaryotes and eukaryotes contain DNA in their genomes. Prokaryotic DNA is present in the cytoplasm since they don’t have a nucleus. But, eukaryotic DNA is present inside the nucleus since they have a true nucleus. Thus, this is the key difference between prokaryotic and eukaryotic DNA. Furthermore, prokaryotic DNA is more compacted and lack of repetitive DNA and introns. On the other hand, eukaryotic DNA contains many genes, repetitive DNA and introns. When comparing the amount of DNA, the eukaryotic DNA amount is higher than the prokaryotic DNA. Moreover, prokaryotic DNA is double-stranded and circular while eukaryotic DNA is double-stranded and linear. Thus, this summarizes the difference between prokaryotic and eukaryotic DNA.
Reference:
1. Nature News, Nature Publishing Group. Available here
2. “Circular Bacterial Chromosome.” Wikipedia, Wikimedia Foundation, 30 Sept. 2018. Available here
Image Courtesy:
1.”Plasmid (english)”By User:Spaully on English wikipedia – Own work, (CC BY-SA 2.5) via Commons Wikimedia
2.”Eukaryote DNA”By Magnus Manske and LadyofHats (Mariana Ruiz) (CC BY-SA 3.0) via Commons Wikimedia